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GATE EC - 2006Q.1 Q.20 Carry One Mark Each.
1. The rank of the matrix
1 1 1 1 1 0 is:
(A) 0
(B) 1
(C) 2
(D) 3
1 1 1
2. P, where Pis a vector, is equal to
2
(A) P P P
( )(B) 2P
+ P
(C) 2P + P
(D)
(
P ) 2P
3.
4.
( P ) ds, where P is a vector, is equal to
(A) P dl(B) P dl
(C) P dl
(D) Pd
A probability density function is of the form
( ) x ( )The value of K is
(A) 0.5
(B) 1
(C) 0.5
(D)
p x = Ke ,x , .
5. A solution for the differential equation
x t" ( ) + 2x t( ) = ( )
with initial condition x( ) = 0 is:
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(A) e 2tu t( )
(B) e u t2t ( )
(C) e u t t ( )
(D) e u tt
( )
6. A low-pass filter having a frequency response H
j( )produce any phase distortion if
(A) A ( ) = C 2, ( ) = k 3
(B) A ( ) = C 2, ( ) = k
(C) A ( ) = C , ( ) = k 2
(D) A ( ) = C , ( ) = k 1
= A ( ) ej ( ) does not
7. The values of voltage ( ) Dacross a tunnel-diode corresponding to peak and valleycurrents areVP and VV respectively. The range of tunnel-diode voltageVDforwhich the slope of its I VDcharacteristics is negative would be
(A) VD< 0
8.
9.
(B) 0 VD< VP
(C) VP VD< VV
(D) VD VV
The concentration of minority carriers in an extrinsic semiconductor underequilibrium is:
(A) directly proportional to the doping concentration
(B) inversely proportional to the doping concentration
(C) directly proportional to the intrinsic concentration
(D) inversely proportional to the intrinsic concentration
Under low level injection assumption, the injected minority carrier current for anextrinsic semiconductor is essentially the
(A) diffusion current
(B) drift current
(C) recombination current
(D) induced current
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10. The phenomenon known as Early Effect in a bipolar transistor refers to areduction of the effective base-width caused by
(A) electron-hole recombination at the base
(B) the reverse biasing of the base-collector junction
(C) the forward biasing of emitter-base junction
(D) the early removal of stored base charge during saturation-to-cutoffswitching.
11. The input impedance ( ) and the output impedance ( ) 0of an ideal trans-conductance (voltage controlled current source) amplifier are
(A) Zi= 0, Z0= 0
(B) Zi= 0, Z0=
(C)
(D)
Zi
Zi
Z= ,0= 0Z =
= ,0
12. An n-channel depletion MOSFET has following two points on itsID VGScurve:(i) V
GS= 0 at ID= 12mA and
(ii) VGS
= 6 Volts at ID= 0
Which of the following Q-points will give the highest trans-conductance gain forsmall signals?
(A)
(B)
(C)
(D)
VGS= 6 Volts
VGS=
3 Volts
VGS= 0 Volts
VGS= 3 Volts
13. The number of product terms in the minimized sum-of-product expressionobtained through the following K-map is (where d denotes dont care states)
1 0 0 1
0 d 0 0
0 0 d 11 0 0 1
(A) 2
(B) 3
(C) 4
(D) 5
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14. Let x t( ) X j( ) be Fourier Transform pair. The Fourier Transform of the signalx (5t 3) in terms ofX j( ) is given as
j3
1 5 j
(A) e X 5
j3
5
15 j
(B) 5 e X 5
1j3 j(C)
e X 5
1 j3
5
j(D) 5 e X
5
15. The Dirac delta
function ( ) is defined
as
(A) ( ) = 1
t = 0
0 otherwise
t = 0
(B) ( ) = 0 otherwise
(C) ( )1
t = 0 ( )
= 0 otherwise
and t dt = 1
(D) ( ) t = 0
( )=
0 otherwiseand t dt = 1
1 2,16. If the region of convergence of1 x n + x2 n is3 < z < then the region of
3
convergence of xn n x2 n includes
(A) 1< z < 33
(B) 2< z < 33
(C) 3< z < 3
2
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(D) 1
3< z < 2
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GGATE EC - 2006
17. The open-loop transfer function of a unity-gain feedback control system is givenby
K
( ) ( ) ( ) .G s
s + 1 s + 2The gain margin of the system in dB is given by
(A) 0
(B) 1
(C) 20
(D)
18. In the system shown below, x t( ) ( sin ) ( ) . In steady-sate, the response
y t( ) will be:
1
(A) 1sint
x t( ) s + 1 y t( )
2 4
(B) 1sint + 2
(C) 1 te
t
4
2 sin(D) sint cos t
19. The electric field of an electromagnetic wave propagating in the positive z-direction is given by
( ) t z
E = ax
sin t z + aysin
+.
The wave is
(A) linearly polarized in the z-direction
(B) elliptically polarized
(C) left-hand circularly polarized
(D) right-hand circularly polarized
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20. A transmission line is feeding 1 Watt of power to a horn antenna having a gain of
10 dB. The antenna is matched to the transmission line. The total power radiatedby the horn antenna into the free-space is:
(A) 10 Watts
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(B) 1 Watt
(C) 0.1 Watt
(D) 0.01 Watt
21. The eigenvalues and the corresponding eigenvectors of a 2 2 matrix are given
byEigenvalue Eigenvector
1 = 18
1=
= 24
11
2=
The matrix is:
(A) 6 2
1
2 64 6
(B) 6 4
(C) 2 4 4 2
4 8(D)
22. For
8 4
the function of a complex variable W = lnZ= + = the u = constant lines get mapped in Z-plane
(where, W u j and Z x+ jy),as(A) set of radial straight lines
(B) set of concentric circles
(C) set of confocal hyperbolas
(D) set of confocal ellipses
23. The value of the contour integral 2 1 dz in posiive sense is
(A)
(B)
(C)
j2
2
j2
=z+ 4
z j 2
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(D)
2
24. The integral3
sin d0
(A) 1
2
(B) 2
3
(C) 4
3
(D) 8
3
is given by
25. Three companies, X, Y and Z supply computers to a university. The percentage ofcomputers supplied by them and the probability of those being defective aretabulated below.
Company % of computers supplied Probability of being defective
X
Y
Z
60%
30%
10%
0.01
0.02
0,03
Given that a computer is defective, the probability that it was supplied by Y is:(A) 0.1
(B) 0.2
(C) 0.3
(D) 0.4
4 2 101
26. For the matrix the eigenvalue corresponding to the eigenvector is:
(A) 2
(B) 4(C) 6
(D) 8
2 4
2
101
d y+k y2= the boundary conditions are27. For the differential equation dx 2 0
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(i) y = 0 forx = 0 and
(ii) y = 0 forx = a
The form of non-zero solutions ofy (where mvaries over all integers) are
m x
(A) y= m
(B) y= m
Amsin
Amcos
m
a
m x
a
(C) y= A xmam
m x
(D) y= A emam
28. Consider the function f t( ) having Laplace transform
( )
=F s
0
+ 1332
-13320
s
Re s > 0
The final value of f t( ) would be:(A) 0
(B) 1
(C) 1 f( ) 1(D)
29. As x is increased from to , the function
x
( )=
f x(A) monotonically increases
(B) monotonically decreases
1e+ e
x
(C) increases to a maximum value and then decreases
(D) decreases to a minimum value and then increases
30. A two port network is represented by ABCD parameters given by
V A B V
1= 2
I
1 C D I2
If port-2 is terminated by RL, the input impedance seen at port-1 is given by
A + BRL
(A) C + DRL
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GATE EC - 2006+ C
(B) ARLBR+ D
L
(C) DRL+ A
BR+ C
(D)
L
B ARL
D + CRL
31. In the two port network shown in the figure below, z12 and z21are, respectively
I1 I2
(A) rc and r0
re I1 ro
(B) 0 and r0
(C) 0 and r0
(D) rc and r0
32. The first and the last critical frequencies (singularities) of a driving pointimpedance function of a passive network having two kinds of elements, are apole and a zero respectively. The above property will be satisfied by
(A) RL network only
(B) RC network only
(C) LC network only
(D) RC as well as RL networks
33. A 2mH inductor with some initial current can be represented as shown below,where s is the Laplace Transform variable. The value of initial current is:
I(s)
0.002s
1 mV+
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(B) 2.0 A
(C) 1.0 A
(D) 0.0 A
34. In the figure shown below, assume that all the capacitors are initially uncharged.
Ifi
( ) = 10u t( ) Volts,0
( ) is given by1K
+
Vi(t)
(A) 0.0048te Volts
(B) 8 1( e 0.004t) Volts(C) 8u t( ) Volts(D) 8 Volts
4F
4K 1F
+
V0(t)
35.
Consider two
transferfunctions
(
)
=
1
a
n
d
G
s
(
)G s
2
2
1 = 2s
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.s + as + b s + as + b
The 3-dB bandwidths of their frequency responses are, respectively
(A) a2
(B) a2
2
4 ,b a + 4b2
+ 4 ,b a 4b
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(C) a2
(D) a2
2
4 ,b a 4b2
+ 4 ,b a + 4b
36. A negative resistance Rnegis connected to a passive network N having driving
point impedance Z1( ) as shown below. For Z2( ) to be positive real,
RnegN
(A)
Z2(s)
Rneg Re Z1( ) ,
Z1( ) ,
Z1(s)
(B) Rneg
(C) Rneg Im Z1( ) ,
Z1
( ) ,(D) Rneg
37. In the circuit shown below, the switch was connected to position 1 at t< 0 and att = 0 , it is changed to position 2. Assume that the diode has zero voltage and a storage time .ts For 0 t ts, Ris given by (all in Volts)
1
2 +
(A) = R5
(B) = +R5
(C) 0
R< 5
5V
5V1K R
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(D)5
< R< 0
38. The majority carriers in an n-type semiconductor have an average drift velocity vin a direction perpendicular to a uniform magnetic field B. the electric field E
induced due to Hall effect acts in the direction(A) v B(B) B v(C) along v
(D) opposite to v
39. Find the correct match between Group 1 and Group 2:
Group 1 Group 2
(E) Varactor diode (1) Voltage reference
(F) PIN diode (2) High frequency switch
(G) Zener diode (3) Tuned circuits
(H) Schottky diode (4) Current controlled attenuator
(A) E - 4 F - 2 G - 1 H - 3
(B) E - 2 F - 4 G - 1 H - 3
(C) E - 3 F - 4 G - 1 H - 2
(D) E - 1 F - 3 G - 2 H - 4
40. A heavily doped n type semiconductor has the following data:
Hole-electron mobility ratio : 0.4Doping concentration :84.2 10 atoms/m3
4
Intrinsic concentration : 1.5 10 atoms/m3
The ratio of conductance of the n type semiconductor to that of the intrinsicsemiconductor of same material and at the same temperature is given by
(A) 0.00005
(B) 2,000
(C) 10,000
(D) 20,000
41. For the circuit shown in the following figure, the capacitor C is initially uncharged.
At t = 0, the switch S is closed. The voltage VCacross the capacitor att = 1 millisecond is:
SC=1F
- V +
1K
10V
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In the figure shown above, the OP-AMP is supplied with 15V and the ground hasbeen shown by the symbol .(A) 0 Volt
(B) 6.3 Volts
(C) 9.45 Volts
(D) 10 Volts
42. For the circuit shown below, assume that the zener diode is ideal with a
breakdown voltage of 6 Volts. The waveform observed across R is:
6V
+
(A)
(C)
12V
12sin t ~
-6V
6V
R VR
(B)
(D)
-12V
6V
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43. A new Binary Coded Pentary (BCP) number system is proposed in which everdigit of a base-5 number is represented by its corresponding 3-bit binary code.For example, the base-5 number 24 will be represented by its BCP code 010100.In this numbering system, the BCP code 100010011001 corresponds to thefollowing number in base-5 system
(A) 423
(B) 1324
(C) 2201
(D) 4231
44. An I/O peripheral device shown in figure (b) below is to be interfaced to an 8085microprocessor. To select the I/O device in the I/O address range D4 H D7 H,
its chip-select( ) should be connected to the output of the decoder shown infigure (a) below:
0A2
A3
LSB
3 - 8
1
2
3
Data
IORD I/O
A7A6
A5
A4
Decoder 456
MSB7
EN
Fig. (a)
IOWR
A1A0
Peripheral
CS
Fig. (b)
(A) output 7
(B) output 5
(C) output 2
(D) output 0
45. For the circuit shown in figure below, two 4-bit parall -in serial-out shift registersloaded with the data shown are used to feed the data to a full adder. Initially, all
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the flip-flops are in clear state. After applying two clock pulses, the outputs of thefull-adder should be
1 0 1 1
MSB LSB
D
CK
Q A S
Shift Registers
FULL ADDER
Clock
0 0 1 1D
CK
Q B
Ci
Q D
CK
Co
(A) S= 0 C0= 0
(B) S= 0 C0= 1
(C) S= 1 C0= 0
(D) S= 1 C0= 1
46. A 4-bit D/A converter is connected to a free-running 3-bit UP counter, as shownin the following figure. Which of the following waveforms will be observed at Vo?
1K
Clock
3-bit
Q2
Q1
Q0
D3
D2
D1
D0
D/A
+
1K
V0
Counter Converter
In the figure shown above, the ground has been shown by the symbol
(A) (B)
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(C)
(D)
47. Two D-flip-flops, as shown below, are to be connected as a synchronous counter
that goes through the following Q Q 10 sequence
00 01 11 10 00 ??DD respectively should be connected as
The inputs 0 and 1D0
CK
Clock
(A) Q1 and Q0
(B) Q0 and Q1
(C) Q1Q and0Q1Q0
(D) Q1Q and0Q1Q0
Q0
Q0
LSB
D1
CK
Q1
Q1
MSB
48. Following is the segment of a 8085 assembly language program:
LXI SP, EFFF H
CALL 3000 H
@
@
3000 H : LXI H, 3CF4 HPUSH PSW
SPHL
POP PSW
RET
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On completion of RET execution, the contents of SP is:
(A) 3CFO H
(B) 3CF8 H
(C) 3FFD H
(D) EFFF H
49. The point P in the following figure is stuck-at-1. The output f will
A
B
P
C
(A) ABC
(B) A
(C) ABC(D) A
50. A signalm t( ) with bandwidth 500 Hz is first multiplied by a signalg t( ) where
( ) = ( ) k ( t 0.5 10 4k)g t
f
R=
The resulting signal is then passed through an ideal lowpass filter with bandwidth1 kHz. The output of the lowpass filter would be:
(A) ( )(B) m t( )(C) 0
(D) m t( ) ( )
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51. The minimum sampling frequency (in samples/sec) required to reconstruct thefollowing signal from its samples without distortion.
( )
=x t
3
sin2 1000t 5
+2
sin2 1000t 7
would be:
3
t t
(A) 2 103
(B) 4 103
(C) 6 103
(D) 8 10
52. A uniformly distributed random variable X with probability density function
( ) 1( ( ) ( ))fx = 10 u x + 5 u x 5Where u( ) is the unit step function is passed through a transformation given inthe figure below. The probability density function of the transformed randomvariable Y would be
y
1
x
(A) fY( ) 1( (
-2.5
) ( ))
2.5
= 5 u y + 2.5 u y 2.5
(B) fY( ) = ( ) + ( )
(C) fY
( )=
0.5
(y+
0.5
)
y 1
(y
) ( )
(D) fY( )0.25
(2.5 + 0.25
) (2.5 + 0.5
) 1( ( ) ( ))= 0.25 y + 2.5 + 0.25 y 2.5 + 10 u y + 2.5 u y 2.5
5
( )53. A system with input x n and output y n is given as = n x n The
system is:
(A) linear, stable and invertible
(B) non-
linear, stable
and non-
invertible
y n sin 6
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.
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(C) linear, stable and non-invertible
(D) linear, unstable and invertible
54. The unit-step response of a system starting from rest is given by
( )c t 1 e 2t for t 0The transfer function of the system is:
(A) 1
1 + 2s
(B) 2
2 + s
(C) 1
2 + s
(D) 2s1 + 2s
55. The Nyquist plot of G j( ) ( ) H j for a closed loop control system, passes through( 1, 0) point in the GH plane. The gain margin of the system in dB is equal to(A) infinite
(B) greater than zero
(C) less than zero
(D) zero
56. The positive values of K and a so that the system shown in the figure below
oscillates at a frequency of 2 rad/sec respectively are
R(s)
( K s(+ 1)
)C(s)
(A) 1, 0.75
(B) 2, 0.75
(C) 1, 1
s3+ as2+ 2s + 1
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(D) 2, 2
57. The unit impulse response of a system is:
( )h t
= e
t, t 0
For this system, the steady-state value of the output for unit step input is equalto
(A) -1
(B) 0
(C) 1
(D)
58. The transfer function of a phase-lead compensator is given by
TsG s( ) = 1+ 3 where T> 0c 1 + Ts
The maximum phase-shift provided by such a compensator is:
(A)
(B)
(C)
(D)
2
3
4
6
59. A linear system is described by the following state equation
0 1
( ) ( ) ( ) = X t = AX t + BU t , A
The state-transition matrix of the system is:
cos t sint (A)
1 0
sint cos t
t cos t sin
(B) sint cos t
(C)
cos t t sin
sint cos t
cos
(D)
t sint
t
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64. In the following figure the minimum value of the constant C, which is to
added to y1( ) such that y1( ) and y2( ) are different, is
y t1( )Quantizer Q with L levels, SameStepsize allowable signal Quantizer
x t( ) withrange V V
dynamic range [-V, V]
+Q y2( )
, 2 2
(A)
C
(B)
(C)
(D)
2
2
12
L
65. A message signal with bandwidth 10 kHz is Lower-Side Band SSB modulated with6
carrier frequency fc1=
10 Hz. The resulting signal is then passed through a9
Narrow-Band Frequency Modulator with carrier frequency fc2=10 Hz.
The bandwidth of the output would be:4
(A) 4 10 Hz6
(B) 2 10 Hz9
(C) 2 10 Hz10
(D) 2 10 Hz
66. A medium of relative permittivityr2=2 forms an interface with free-space. A
point source of electromagnetic energy is located in the medium at a depth of 1meter from the interface. Due to the total internal reflection, the transmittedbeam has a circular cross-section over the interface. The area of the beam cross-section at the interface is given by
(A) 2 m2
(B) 2m2
(C) m22
(D) m2
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67. A medium is divided into regions I and II about x= 0 plane, as shown in the
figure below. An electromagnetic wave with electric field E1= 4ax + 3ay + 5az isincident normally on the interface form region-I. The electric field E2in region-II
at the interface is:
Region I
= 0, ,
Region II
= 0, = ,
1
=1= 0 2 = 2 0
(A) E2= E1
x0
(B) 4ax+
0.75ay 1.25az
(C) 3ax+3ay
+5az
(D) 3ax+3ay
+5az
68. When a plane wave traveling in free-space is incident normally on a medium
having r= 4.0, the fraction of power transmitted into the medium is given by
(A) 8
9
(B) 1
2
(C) 1
3
(D) 5
6
69. A rectangular waveguide having TE10 mode as dominant mode is having a cutoff
frequency of 18-GHz for the30rectangular waveguide is:
(A)5
cms3(B) 5 cms
(C) 5 cms2
(D) 10 cms
TE mode. The inner broad-wall dimension of the
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70. A mast antenna consisting of a 50 meter long vertical conductor operates over aperfectly conducting ground plane. It is base-fed at a frequency of 600 kHz. Theradiation resistance of the antenna in Ohms is:
2
2(A)
(B)
(C)
(D)
5
2
5
24
520 2
Common Data Questions:
Common Data for Questions 71, 72, 73:
In the transistor amplifier circuit shown in the figure below, the transistor has thefollowing parameters:
DC= V = V h , h 60,BE 0.7 , ie fe
The capacitance Cccan be assumed to be infinite.
53K
5.3K
Cc
12V
+
Vc
~ Vs
In the figure above, the ground has been shown by the symbol
71. Under the DC conditions, the collector-to-emitter voltage drop is:
(A) 4.8 Volts
(B) 5.3 Volts
(C) 6.0 Volts
(D) 6.6 Volts
72. IfDC is increased by 10%, the collector-to-emitter voltage drop
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(A) increases by less than or equal to 10%
(B) decreases by less than or equal to 10%
(C) increases by more than 10%
(D) decreases by more than 10%
73. The small-signal gain of the amplifier cs is:
(A) -10
(B) -5.3
(C) 5.3
(D) 10
Common Data for Questions 74, 75:
Let g t( ) = p t( ) *p t( ) , where * denotes convolution and p t( ) ( ) (1)u t( ) being the unit step function = u t u t with
74. The impulse response of filter matched to the signals t( ) = g t( ) (given as:
(A) s(1 t )(B) s (1 t )(C) s t( )(D) s t( )
75. An Amplitude Modulated signal is given as
t 2 *) g t( ) is
( ) = ( ( ) + ( ) ) txAM 100 p t 0.5g t cos c
in the interval 0 t 1. One set of possible values of the modulating signal and
modulation index would be
(A) , 0.5
(B) ,1.0
(C) , 2.0
(D) t2, 0.5
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Linked Answer Questions: Q.76 to Q.85 Carry Two Marks Each.
Statement for Linked Answer Questions 76 & 77:
A regulated power supply, shown in figure below, has an unregulated input (UR) of 15Volts and generates a regulated output Vout. Use the component values shown in the
figure. 15V (UR)
1K
6V
+
Q1
12K10
24K
+
Vout
In the figure above, the ground has been shown by the symbol
76. The power dissipation across the transistor Q1 shown in the figure is:
(A) 4.8 Watts
(B) 5.0 Watts
(C) 5.4 Watts
(D) 6.0 Watts
77. If the unregulated voltage increases by 20%, the power dissipation across thetransistor Q1
(A) increases by 20%
(B) increases by 50%
(C) remains unchanged
(D) decreases by 20%
Statement for Linked Answer Questions 78 & 79:
The following two questions refer to wide sense stationary stochastic processes
78. It is desired to generate a stochastic process (as voltage process) with powerspectral density
S ( ) 16= +
16 2
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By driving a Linear-Time-Invariant system by zero mean white noise (as voltageprocess) with power spectral density being constant equal to 1. The system whichcan perform the desired task could be:
(A) first order lowpass R-L filter
(B) first order highpass R-c filter
(C) tuned L-C filter(D) series R-L-C filter
79. The parameters of the system obtained in Q.78 would be
(A) first order R-L lowpass filter would have R = 4 L = 4H
(B) first order R-C highpass filter would have R = 4 C = 0.25F
(C) tuned L-C filter would have L = 4H C = 4F
(D) series R-L-C lowpass filter would have R = 1, L = 4H, C = 4F
Statement for Linked Answer Questions 80 & 81:
Consider the following Amplitude Modulated (AM) signal, where fm< B:
x ( ) = ( f t ) cos 2 f tAM 10 1 + 0.5 sin2 m c
80. The average side band power for the AM signal given above is:
(A) 25
(B) 12.5
(C) 6.25
(D) 3.125
81. The AM signal gets added to a noise with Power Spectral Density Sn( ) given inthe figure below. The ratio of average sideband power to mean noise powerwould be:
(A)25
8N B
Sn( )
(B)
0
25
4N B
N02
(C)
0
25
2N B
(D)
0
25N B
fcB fc + fcB fc B fc fc+ B
0
Statement for Linked Answer Questions 82 & 83:
Consider a unity-gain feedback control system whose open-loop transfer function is:
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( ) = +
G sas21
s
82. The value of a so that the system has a phase margin equal to
approximately equal to(A) 2.40
(B) 1.40
(C) 0.84
(D) 0.74
is4
83. With the value of a set for a phase-margin of
,4
the value of unit-impulse
response of the open-loop system at t= 1 second is equal to(A) 3.40(B) 2.40
(C) 1.84
(D) 1.74
Statement for Linked Answer Questions 84 & 85:
A 30-Volts battery with zero source resistance is connected to a coaxial line ofcharacteristic impedance of 50 Ohms at t = 0 second terminated in an unknown resistiveload. The line length is that it takes 400 s for an electromagnetic wave to travel fromsource end to load end and vice-versa. At t
=400
s, the voltage at the load end is
found to be 40 Volts.
84. The load resistance is
(A) 25 Ohms
(B) 50 Ohms
(C) 75 Ohms
(D) 100 Ohms
85. The steady-state current through the load resistance is:
(A) 1.2 Amps(B) 0.3 Amps
(C) 0.6 Amps
(D) 0.4 Amps
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